铝合金非枝晶组织感应加热演变动力学研究  

Dynamic study on microstuctural evolution of non-dendritic alloys during induction reheating

作　　者：张恒华[1] 邵光杰[1] 许珞萍[1] 徐霖[1] 

机构地区：[1]上海大学材料学院,上海200072

出　　处：《材料科学与工艺》2005年第2期205-208,共4页Materials Science and Technology

摘　　要：应用图象分析法系统研究了非枝晶A356铝合金感应加热时的组织演变规律,结合非线性拟合和晶粒长大动力学等研究,结果表明:A356铝合金初生α-Al晶粒在不同感应加热温度下的长大规律均符合奥斯瓦尔德熟化关系式Rn-R0n=kt,在540℃-600℃的保温温度范围内,n值在2-3之间,k值在0.7-155之间.在固液两相区加热保温,α-Al晶粒长大速度要明显高于固相区加热保温时的长大速度,这与液相扩散系数要远大于固相的扩散系数相关.α-Al晶粒长大方式为,在固相区加热保温,共晶组织中β-Si颗粒通过扩散不断凝聚、粗化,致使晶界逐步消失,从而使α相合并长大,而在固液两相区加热保温,晶粒长大方式更为复杂,但圆整度均没有提高.In this paper, the microstructural evolution of non-dendritic A356 alloys during induction reheating has been studied by means of metallography and image analysis method. It is shown by combining the non-linear fitting and dynamic studying of grain growth that the evolution of primary α-Al grain in the A356 aluminum alloy during induction heating accords with the law of Oswald, Rn- R0n = kt, where 2.≤n. ≤3, 0.7. ≤k. ≤155 under soaking temperature of 540℃-600℃. The growing rate of primary α-Al soaked in the semisolid state is much higher than that of soaked in the solid state, this is because the diffusion rate in the semisolid state ie markedly higher than that in the solid phae. The primary α-Al grains merge each other due to the diffusion and coalescence of β-Si particles when it is soaked in the solid phase, while the growing pattern of primary α- Al grains is more complex when it is soaked in semi-solid state, however, the spheroidized degree of primary α-Al grains keep almost same during soaking whether the temperature is in the solid state or in the semi-solid state.

关 键 词：铝合金 组织演变 晶粒长大 感应加热 

分 类 号：TG1[金属学及工艺—金属学]